Diodes ZXLD383 User Manual

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ZXLD383

SINGLE OR MULTI CELL LED DRIVER SOLUTION

Summary

The ZXLD383 is a single or multi cell LED dri ver des ig ned for applications requiring step-up voltage conversio n from a ver y low input voltage. The IC generates constant current pulses that are ideal for dr iving single or multiple LEDs over a wide range of operating voltages. It includes an on/off enable input t hat can be driven directly from a photoc ell array or an open collector/drain logic output. The enable input features an ultra-lo w voltage drop diode to ground, elim inating the need for a photocell array isolation diode in Garden Light applications.

The ZXLD383 uses a PFM control technique to drive an internal switching transistor which exhibits a low saturation resistance. This ensures high efficiency, even for input voltages as low as 1.0V.

The IC can start up under full load and operates down to an input voltage of below 0.9V. The ZXLD383 is offered in the space s aving TSOT23-5 package or in die form, offering an excellent cost vs. performan ce

solution for single cell LED driving applications.

Features

• 85% Efficiency

• User adjustable output current

• Single cell operation

• Low saturation voltage

• TSOT23-3 package

• Available also in die form

• Simple application circuit

Application

• Garden lights

• Door/pathway illumination

• LED flashlight and torches

• LED backlights

• White LED driver

• Gated boost supply generator

Typical Application Circuit

Pin Assignments

1

ENA

NC

2

3

GND

TSOT23-3

(Top View)

5

CC

V

4

V

OUT

ZXLD383

Document number: DS32189 Rev. 3 - 2

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Block Diagram

Diode Array

NIMH

1.2V

ZXLD383

ENA

Dch

Fig 1. ZXLD383 Block Diagram

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ZXLD383

VCC

VOUT

Pulse Control

CoffCon

Rsense

GND

L1

LED

Pin Description

Pin No. Name Description

1 ENA Enable / Photodiode array battery charge input 2 GND Ground 3 NC Not connected (internally open circuit)

4 5

V

OUT

CC

ZXLD383

Document number: DS32189 Rev. 3 - 2

Switch output external inductor/LED Supply voltage, generally Alkaline, NiMH or NiCd single cell

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Absolute Maximum Ratings

Parameter Rating Unit

Supply Voltage (VCC) Output Voltage (V Enable Voltage (V

OUT ENA

)

) Supply Current 20 mA Output Switch Current 800 mA Power Dissipation (TSOT23-3) 450 mW Power Dissipation Die 1 W Operating Temperature Range -20 to 85 °C Storage Temperature Range -55 to 150 °C

-0.6 to 6 V

-0.6 to 20 V

-1 to 3.5 V

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ZXLD383

Electrical Characteristics Measured at T

Parameter Conditions

= 25°C, L = 6.8µH, I

AMB

= 0 and VCC = 1.5V unless otherwise specified.

ENA

Limits

Min Typ. Max

Units

Supply Voltage Operating Range L = 10μH 0.9 3.3 V Minimum Supply Start-up Voltage L = 10μH 0.8 0.9 V Supply Current Quiescent

Supply Current Shutdown Supply Current Under-Voltage

2 4 8 mA

= VCC – 0.8V

V

ENA

VCC = 0.6V

17 30 µA 20 µA

Switch Current At turn-off 250 320 400 mA Switch Saturation Voltage

Switch Leakage Current Mean LED Current Efficiency

I

OUT

V V V

OUT LED LED

= 200mA

= 20V, V = 3.5V = 3.5V

ENA

= 0V

100 300 mV 10 µA

40 50 65 mA

85 %

Operating Frequency

V

LED

= 3.5V

330 kHz

Discharge Pulse Width 0.7 1.5 2.5 µs

Enable Input Threshold Enable Input Current Enable Input Voltage

V I

ENA

= 0.2V

= -20mA

VCC - 0.8 VCC - 0.6 VCC - 0.2

0 -11 -20 µA 0 -90 -250 mV

V

ZXLD383

Document number: DS32189 Rev. 3 - 2

3 of 10

www.diodes.com

May 2010